Adventure Week, the latest weeklong event for Pokémon Go, has promised increased spawns for rock-type Pokémon, including fossil types like Aerodactyl, Omanyte and Kabuto. Additionally, it has increased the rate at which your buddy Pokémon find candy by four times to encourage players to get out and, well, have adventures.

Unfortunately, players trying to evolve Eevee into Umbreon or Espeon using the buddy system trick are in for a pretty nasty surprise if they've been tracking their progress towards its two Gen 2 evolutions in a certain way. Confused? Don't worry, we're here to explain.

According to a post on the Silph Road subreddit, a user named justHagey reported that they'd evolved their Eevee after getting two candies while buddied up with them. Normally this isn't a problem since Eevee gains a candy every 5km. However, with the increased rate of buddy candy acquisition, justHagey ended up evolving their Eevee while it was still only with them for 8.1 kilometers — so they ended up with a Vaporeon instead.

JustHagey took this to mean that for the buddy trick to work, you'll need two buddy candies gained and also to have walked 10 km with them. Some posters on the Silph Road have objected to this on the grounds that justHagey didn't use a "fresh" 0 km buddy Eevee to test their hypothesis.

Whether or not you ascribe to the Silph Road's rather stringent views on variable testing, it seems like the answer — at least where Eevee's Gen 2 evolutions are concerned — is "better safe than sorry." If you've already used up your nicknames on an Umbreon and an Espeon, it's probably worth it to make sure that you've walked at least 10 km with them until the event ends, regardless of how much candy you've acquired with them.

If you're more interested in the main games, here's the latest on a possible Pokémon title on the Nintendo Switch: Pokémon Stars. And if you're itching to learn about the other mobile Nintendo games, check out our coverage of Fire Emblem Heroes and Super Mario Run.